1. Field of the Invention
This invention relates to a structural member of electric or electronic device, particularly to a surface-treated metal body utilizable as a substrate of a photoconductive member such as an electrophotographic photosensitive member, etc., and to a process for producing the same,.a photoconductive member using the surface-treated metal body, and a rigid ball for treating the metal body surface.
2. Related Background Art
Various cutting or grinding treatments have been applied to a metal body surface to give a desired surface shape, depending on their uses.
For example, metal bodies of plate shape, cylindrical shape, endless belt shape, etc. are used as substrates (supports) of a photoconductive member such as electrophotographic photosensitive member, etc., and their surfaces are finished by cutting treatment to form a mirror surface, etc., as a preliminary step for forming layers such as a photoconductive layer, etc. on the support. For example, the surfaces are finished to a surface flatness within a given range by diamond cutting tool cutting with a lathe, a milling machine, etc., or sometimes to an irregularity of given or desired shape to prevent an interference fringe.
However, in the formation of such a surface by cutting, the cutting tool contacts fine ingredients existing near the surface of a metal body, such as rigid alloy components, oxides, etc. or blisters, thereby lowering the cutting efficiency, and also the surface defects due to the ingredients, etc. are liable to appear by the cutting. For example, an aluminum alloy, when used as a support metal body, has ingredients such as intermetallic compounds, e.g. Si-Al-Fe, Fe-Al, TiB.sub.2, etc. or oxides of Al, Mg, Ti, Si, and Fe or blisters by H.sub.2 in the aluminum structure, and also has surface defects such as grain boundary discrepancy taking part between the adjacent Al structures of different crystal orientations. When, for example, an electrophotographic photosensitive member is made from a support having such a surface defect, no uniform layers can be obtained, and consequently the photosensitive member cannot have uniform electrical, optical and photoconductive characteristics, and fails to produce a good image. That is, such a photosensitive member cannot meet the practical purpose.
The cutting treatment also has other problems such as producing of powdery cutting wastes, consumption of cutting oil, complicated disposal of the powdery cutting wastes, and treatment of cutting oil remaining on the cut surface.
Besides the cutting means, the conventional means for plastic deformation, such as sand blast, shot blast, etc. are used to control the surface flatness or surface roughness of the metal body, but the shape irregularity, precision, etc. of the metal body surface cannot be exactly controlled by such means.
Furthermore, when the surface roughness is attained by the foregoing means, an irregular state, for example, a relatively large and acute irregular state, is exposed of the surface, and thus the durability of the resulting photosensitive member is considerably deteriorated against repeated frictions by a cleaning means, etc.